Cleanup and Clarification

Hello. This wiki page while very exhaustive in content is tangenital with a fractured flow. It seems the prefered method for straight forward system encryption in single drive systems is to use a combination of Luks and LVM2 - this solution provides for an encrypted swap that does not have any issues with hibernation or suspend. I propose making this section the first part of the wiki page to follow the justification for using Luks with the rather large volume of detailed information to follow in other sections. If there are no objections I'll go ahead and structure this in the wiki page itself.
Vinhsynd 9:55, 30 September 2010 (CDT)

Hey all, I was trying to encrypt my hd using this page as a reference, but it was a bit difficult to read. As such, I'm going to try to clean things up a bit. It would be nice if there were a clean set of instructions with tips along the way for specialized setups.

On a related note... would anyone mind if some of the posts on this page were erased? There are a number of posts from 2007, 2008...
--Arcanazar 13:22, 21 August 2010 (EDT)

I'm considering to do some editing and rewriting of this page, mainly in part "4 The Steps". The content would mostly stay the same, safe for some changes introduced with the newer versions of arch, where less console switching and module loading is needed. On the same subject should we drop, or move to a subsection, the parts related to versions 0.72 of arch?

Does anyone have objections to my plans, or should I just go ahead and we can revert back if it doesn't fit?
WhiteMagic 12:56, 24 May 2007 (EDT)

This is new territory for me, but I want to implement this topic myself soon. I'll start with removing some duplicated content. T1nk3r3r (talk) 07:25, 16 June 2013 (UTC)

Luks and suspend2

Would it be worth adding a section on opening encrypted drives from the kernel command line, or more specifically on combining luks and suspend2? As far as I can tell opening a swap partition from crypttab doesn't make it available in time to resume from, but adding the following to a lilo append option does:

resume2=swap:/dev/mapper/swap cryptdevice=/dev/sda2:swap

I'm not sure if this is the correct/best way of doing this, though, and didn't see other documentation.

Proposed update of the section 'Storing the key between MBR and 1st partition'

Background

I tried to setup automatic mount of my LUKS encrypted /home using a keyfile stored between MBR and first partition header of my USB key following this wiki page and realized that it didn't work out because the howto is incomplete. I had to manually go through the encrypt hook to figure out what it does. To save other users this tiresome work that cost me hours until all finally worked out the way I wanted it I propose to update the mentioned section in the following way. Suggestions welcome. Maybe it should be noted in the parent section that /etc/crypttab conflicts with using the howto presented here.

Add the temporary keyfile we created before with cryptsetup:

cryptsetup luksAddKey /dev/hda3 secretkey

That should return you output like this:

Enter any LUKS passphrase:
key slot 0 unlocked.
Command successful.

Next you'll have to write the key directly between MBR and first partition.

WARNING: you should only follow this step if you know what you are doing - it can cause data loss and damage your partitions or MBR on the stick!

If you have a bootloader installed on your drive you have to adjust the values. E.g. GRUB needs the first 16 sectors, you would have to replace seek=4 with seek=16; otherwise you would overwrite parts of your GRUB installation. When in doubt, take a look at the first 64 sectors of your drive and decide on your own where to place your key.

OFFSET and SIZE match in this example, but this is coincidence - they can differ (and often will). An other possible example could be (if you use skip=16 in the 'dd' command above to protect the bootloader)

The encrypted block device BLOCKDEVICE will then be mapped to /dev/mapper/MAPPING_TARGET

Note: You will _not_ need to have /etc/crypttab setup for this device then (but maybe you want to use it for other encrypted devices where you want to enter the passphrase manually or e.g. use a keyfile stored on this afterwards decrypted partition)! But don't forget to activate the encrypt hook in /etc/mkinitcpio.conf (_before_ the filesystems hook)

That's all, reboot and have fun! And look if your partitions still work after that ;-).

LVM2 and LUKS

I'm quite sure this section is misleading. You have to setup up encryption before LVM2 partitions on the decrypted device.

And you have to add the "encrypt" hook before the "lvm2" hook, because you need to make the decrypted device available before LVM2 imports volume groupe and makes logical volumes available.

Yet this chapter tends to tell the other way round. Is my English so bad ?

- This section is misleading. What the author meant was if you encrypt the contents of LVM partitions, THEN you have to move the lvm2 hook before the encrypt hook. I made a few small changes, so other newbies (like me) don't end up with an unbootable system.

-- I also agree that the section needs a further overhaul, assuming here everyone commenting means the "Encrypting and LVM Setup" (because "LVM2 and LUKS" is not in the TOC). Having encrypt over (i.e. before) LVM is def the typical and easiest setup (and this should be expanded on more clearly in the wiki like in the link above I agree). However, all methods have a usecase. It depends what the user wants to achieve. Time permitting, the differences should be worked out. --Indigo (talk) 19:53, 18 September 2012 (UTC)

Prepare hard drive

The actual text is:

Skip the Partitioning and Auto-Prepare business and go straight to "Set Filesystem Mountpoints". When asked for your / (root) partition, do NOT select /dev/sda3 as you normally would. Select /dev/mapper/root instead. Similarly, use /dev/mapper/home instead of /dev/sda4 as the partition to be mounted as /home. The same is valid for a swap partition which is set up like the home partition. Make sure you mount /dev/sda1 as the /boot partition or else the installer will not properly set up the bootloader.

but the Arch Linux installer says:
[code]
/dev/sda1
/dev/sda2
/dev/mapper/root
/dev/mapper/lvm-home
/dev/mapper/lvm-root
/dev/mapper/lvm-swap
/dev/mapper/lvm-tmp
[/code]
When asked for / (root) partition: is it /dev/mapper/root or /dev/mapper/lvm-root. I suppose it is the first one because the second one does not match.

Decryption of root during boot with the assistance of UDEV when key is stored on USB drive between MBR and 1st Partition

The instructions in the wiki were very helpful but a bit confusing/lacking when it comes to getting Decryption via USB keyfile stored between MBR and 1st Partition.

When modifying your bootloader you will be unable to use /dev/disk/by-uuid because you are not referencing a filesystem. You wouldn't want to use /dev/sd[x] because this can and will change depending on what other drives and media you have connected during boot. The best bet is to create a udev rule that will exist in early userspace to alias your usb drive to an arbitrary name, in this case "usbkey". The rule must be added to the initial ramdisk so it can be read and processed to alias your drive at /dev/usbkey before root decryption is attempted via the key hidden on the drive.

System_Encryption_with_LUKS#Using_udev runs you through the initial steps you need to create a basic rule based on the USB drive's serial number. That is the very same rule I used. I named the rules file "62-usbkey.rules" and placed it in /etc/udev/rules.d/.

Now modify /etc/mkinitcpio.conf, look for the "FILES" section and add the udev rule that you created above:

# FILES
# This setting is similar to BINARIES above, however, files are added
# as-is and are not parsed in any way. This is useful for config files.
# Some users may wish to include modprobe.conf for custom module options
# like so:
# FILES="/etc/modprobe.d/modprobe.conf"
FILES="/etc/udev/rules.d/62-usbkey.rules"

systemd addidtions

systemd requires lvm-on-cryptdevice.service active in order to open LVMs on cryptdevices that are not the root partition (which is handled by the initrd).

after 2012.07.15

What change with the new installation process and systemd change ? If I understand correctly parts related to /etc/rc.conf files are no longer useful but what's the correct way now ? thanks --Martvefun (talk) 00:27, 9 January 2013 (UTC) -> question and response asked[1]

Encrypted swap With suspend-to-disk support

Shouldn't the openswap hook go after the encrypt hook? Otherwise you have to always open the root device prior to the swap, even on resume.

You meant to write ".. the openswap go before encrypt ..?" which sounds like a reasonable suggestion. Have you tried it? (I have not). Maybe it works still (without manual unlocking of root) because of the kernel parameter resume=.. In Debian it would go after, but there the key for swap is derived by the hook from the root master key (hence not input extra for swap, which is elegant).--Indigo (talk) 22:06, 6 February 2013 (UTC)

Feature of Grub2 to decrypt /boot

Original comment by Chehri on 8.6.13, moved from [Dm-crypt_with_LUKS#Creating_Disk_Partitions] to here:
It is now possible to include /boot on a LUKS container thanks to grub 2.00. Zack Buhman (buhman) has proposed a patch which allows this. This allows kexec to be used to start a new kernel in remote situations. It also removes any possibility of the kernel being tampered with (though grub is still unencrypted; store on a removable drive for added safety).

Interesting patch/idea. I moved the out-of-date box here to discussion first for the following reason:

The patch you link to is proposed and not even commented on, i.e. it is not in the encrypt hook. Having it there as out-of-date in this general Luks section at the beginning will confuse new readers totally. Another reason is that the Luks page in that section is general, not grub specific. Everything there can be setup with standard Arch [core], i.e. also Syslinux.

I hope you agree to that, if not let's please discuss it. Thanks.

I think the best way forward for the contribution would be to draft a subsection under 3.2 (e.g. as 3.2.7), we have different hook modifications there for the swap. (later on there is a specific section on encrypted keyfiles too where it might fit well). Once the section is complete and accurate to modify a standard Arch, one could link to it from the general section above. Once something like that goes into the vanilla Arch-encrypt hook, it should definetely be described earlier. Another (different) point would be to discuss the pros/cons security-wise of such a modification a bit. That could be done in the subsection too. --Indigo (talk) 17:35, 8 June 2013 (UTC)

AIF

I just came here to try to update information concerning mkinitcpio.conf for LVM-on-LUKS. I'm not sure I've found everything to update as there seem to be several pages which cover similar but not quite the same information.

I was wondering, though, what was planned for the AIF section. I think the inclusion of this is unnecessarily confusing to new users since this has been deprecated for quite some time.

This article has lots of very interesting content, but yeah some parts are outdated just like that one: AIF is dead/suspended (don't remember the official status), that section can go. -- Kynikos (talk) 13:16, 16 July 2013 (UTC)

Thanks for bringing it up, I removed it (you can find it on my user-page for ~ a month). Next needing clean-up is 8.1 - 8.4 (please state your opinion below, thanks!). --Indigo (talk) 20:16, 16 July 2013 (UTC)

Encrypting a LVM setup (ex section 8)

The content in sections 8.1 to 8.4 has to be updated, particularly the AIF and /etc/rc.conf references must go. Since another user created a "Encrypted LVM" stub article, which (arguably) has style problems but is a good read otherwise, I see two alternatives for section 8:

A. (1) Remove all outdated install instructions from 8.1 to 8.4, (2) link to the "Encrypted LVM" stub article for users looking for verbose LVM/LUKS install instructions, but (3) keep the LVM short instructions in this article too as a quick reference section. Next, (4) the "Encrypted LVM" should then properly link back properly to the "LUKS" page (particularly to the explanations about the LUKS options)!

B. The second option would be to (5) move the stub article here into section 8, but this would require a major work to make it fit with the rest of the page (double content, a lot of linking up/down).

Both can be done, I prefer A, also because the LUKS page itself is rather huge already. In fact I added links over to that stub page a while back so that new users find it so noone stumbles over /arch/setup et al.
Maybe you have another idea than A or B. Opinions? --Indigo (talk) 20:16, 16 July 2013 (UTC)

Yep, if you could take the time to implement A it would be a great improvement. -- Kynikos (talk) 07:42, 20 July 2013 (UTC)

Glad you approve. I have done a re-work today of that; could not wait somehow. Would be good, if someone has a look over it in case I missed out on something. The editing was not that much, more trying not to loose great content which still applies. Still missing is A(4) from above (backlinking from the stub page) and removing the merge-tag in the section (ex sec 8). I also moved some sections to get connected content together (please check TOC). I hope it is not only better in my view. Anyone missing something can find the original section 8 (LUKS-LVM) pasted on my user-page for the time being. --Indigo (talk) 17:44, 20 July 2013 (UTC)

I've taken the time to check your edits (you made it a lot easier by properly commenting really everything), and I like what you've done, it's a very good job!! :)

Yes, A(4) still has to be done, while about removing the Merge template I don't know, maybe "Encrypting a LVM setup" can still be merged to Encrypted LVM, what do you think? (This would be kind of a C. alternative, opposed to B.).

Thanks for taking the time to check it! Currently I would leave it at A as opposed to C, for two reasons: Firstly, the Encrypted LVM works/reads well with the two main setup options shown. Then it picks up different important subjects (gpt, multiple disks) but lacks some of the setup the LVM example this page has (e.g. nowhere on Encrypted LVM you find the word "swap"). So a merge would entail rework of the page in order not to loose content in the merge. Or even adding another example there (better not imho). Secondly, the other installation instructions on this page LUKS#Encrypting_a_system_partition are deliberately describing the simplest encrypted setup. So, the LVM install example here adds options which a reader might want to mix in (e.g. swap, separate /home; maybe those options are worth a mention revisiting it). I think about it again, but currently I would consider the current split easier comprehensible for both pages and outweighing the duplicity (of LVM commands). Any further LVM install tricks should of course be on the other pages, LUKS tricks here. Thoughts? --Indigo (talk) 21:06, 21 July 2013 (UTC)

All right, you convinced me, let's leave it there, thanks again ^^ (this discussion will stay open until all the remaining points are implemented) -- Kynikos (talk) 10:06, 22 July 2013 (UTC)

Okies, I added three (sublime:p) link-backs in the Encrypted LVM howto where I would consider LUKS pointers useful at the least. I will surely revisit the page, but at current A(4) is done from my view. Maybe the merge tag can go for now. Next bits of re-work here on the page may be further streamlining the starting section with better guidance through the page, but that's out-of-bounds this discussion (more the first point on this page). I also marked some old discussions here as closed. It would be nice if you or someone else could look at them sometime and rm as appropriate. Thanks. --Indigo (talk) 20:04, 25 July 2013 (UTC)

Well done, you can remove the merge template and close this discussion then (don't worry, all closed discussions are removed sooner or later). If you will want to discuss more changes to this article, do not hesitate to open another thread. -- Kynikos (talk) 04:51, 27 July 2013 (UTC)